import sys
if len(sys.argv) != 4:
    print('Usage: python calc.py operand [+|-] operand')
    sys.exit(0)
left=sys.argv[1]
operator=sys.argv[2]
right=sys.argv[3]
if operator == '+':
    result=int(left)+int(right)
elif operator == '-':
    result=int(left)-int(right)
elif operator == '*':
    result=int(left)*int(right)
elif operator == '/' and right != '0':
    result=int(left)/int(right)
else:
    print('Entry error.')
    exit()
print(result)
